title: Role of capsular polysaccharide (CPS) in biofilm formation and regulation of CPS production by quorum-sensing in Vibrio vulnificus.
abstract: Extracellular polysaccharides, such as lipopolysaccharide and loosely associated exopolysaccharides, are essential for Vibrio vulnificus to form biofilms. The role of another major component of the V. vulnificus extracellular matrix, capsular polysaccharide (CPS), which contributes to colony opacity, has been characterized in biofilm formation. A CPS-deficient mutant, whose wbpP gene encoding UDP-GlcNAc C4-epimerase was knocked out, formed significantly more biofilm than wild type, due to increased hydrophobicity of the cell surface, adherence to abiotic surfaces and cell aggregation. To elucidate the direct effect of CPS on biofilm structure, extracted CPS and a CPS-degrading enzyme, α-N-acetylgalactosaminidase, were added in biofilm assays, resulting in reduction and increment of biofilm sizes respectively. Therefore, it is suggested that CPS play a critical role in determining biofilm size by restricting continual growth of mature biofilms. Since CPS is required after maturation, CPS biosynthesis should be controlled in a cell density-dependent manner, e.g. by quorum-sensing (QS) regulation. Analysing transcription of the CPS gene cluster revealed that it was activated by SmcR, a QS master regulator, via binding to the upstream region of the cluster. Therefore, CPS was produced when biofilm cell density reached high enough to turn on QS regulation and limited biofilms to appropriate sizes.
authors.affiliation: Department of Life Science, Sogang University, Seoul, 121-742, Korea.
authors.forename: Kyung-Jo
authors.initials: KJ
authors.lastname: Lee
authors.forename: Jeong-A
authors.initials: JA
authors.lastname: Kim
authors.forename: Won
authors.initials: W
authors.lastname: Hwang
authors.forename: Soon-Jung
authors.initials: SJ
authors.lastname: Park
authors.forename: Kyu-Ho
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D016667:Bacterial Capsules / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D002238:Carbohydrate Epimerases / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D008070:Lipopolysaccharides / Q000502:physiology*; D005810:Multigene Family; D053038:Quorum Sensing; D015398:Signal Transduction; D041261:Vibrio vulnificus / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D000118:Acetylglucosaminidase; D002238:Carbohydrate Epimerases; C023223:UDP-N-acetylglucosamine 4-epimerase